A new supported liquid membrane (SLM) system for the selective transport of silver ion is introduced. The SLM used is a thin porous membrane impregnated with a recently synthesized mixed aza-thioether crown containing a 1,10-phenanthroline sub-unit dissolved in nitrophenyl octyl ether. In the presence of thiosulfate as a metal ion acceptor in the strip solution, the transport of silver occurs almost quantitatively after 3 h. The selectivity and efficiency of silver transport from aqueous solution containing excess amounts of Mg2+, Ca2+, Sr2+, Ba2+ Co2+, Ni2+ Cu2+ Zn2+, Pb2+, Cd2+ and Hg2+ ions were investigated. (C) 2003 Elsevier Science B.V. All rights reserved.